Researchers identified several biomarkers to aid in risk stratification models for predicting severe and fatal coronavirus disease 2019 (COVID-19), according to meta-analysis results published in Clinical Chemistry and Laboratory Medicine.

To evaluate the discriminative ability of biomarkers in patients with and without severe or fatal COVID-19, Brandon Michael Henry, MD, of the cardiac intensive care unit at The Heart Institute at Cincinnati Children’s Hospital Medical Center in Ohio, and colleagues identified studies reporting hematologic, biochemical, and immunologic laboratory values for patients with COVID-19. The studies were divided based on disease severity (severe vs nonsevere) and mortality (nonsurvivors vs survivors).

The meta-analysis included 21 studies, which together, comprised 3377 patients and 33 laboratory parameters. Of those, 18 studies (2984 patients) compared laboratory findings of patients with severe and nonsevere disease and 3 studies (393 patients) compared survivors and nonsurvivors.

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Both severity and mortality groups had increased white blood cell (WBC) counts, although this increase was more significant in patients who died (weighted mean difference [WMD], 0.41 x 109/L vs 4.15 x 109/L, respectively). In addition, severity cohort and mortality cohorts both had decreased lymphocyte counts (−0.28 x 109/L and −0.44 x 109/L, respectively). Platelet counts were significantly associated with severity and fatality (−23.36 × 109/L and −48.3 × 109/L, respectively).

The levels of numerous biomarkers of inflammation, cardiac and muscle injury, and liver and kidney function, as well as measures of coagulation were significantly elevated in patients with severe and fatal disease relative to patients with nonsevere and nonfatal disease. IL-6 (WMD, 1.70 pg/mL), C-reactive protein levels (WMD, 37.78 mg/L), and serum ferritin (408.28 ng/mL) were strong indicators for severe COVID-19.

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Limitations of the study included variable definitions of disease severity, unclear timepoints for laboratory collection, small sample size (mortality comparison), and lack of generalizability (nearly all studies were conducted in China).

“In hospitalized patients with respiratory distress, we recommend clinicians closely monitor WBC count, lymphocyte count, platelet count, IL-6, and serum ferritin as markers for potential progression to critical illness,” the authors concluded.


Henry BM, de Oliveira MHS, Benoit S, Plebani M, Lippi G. Hematologic, biochemical and immune biomarker abnormalities associated with severe illness and mortality in coronavirus disease 2019 (COVID-19): a meta-analysis [published online April 10,2020]. Clin Chem Lab Med. doi:10.1515/cclm-2020-0369